Migration imaging system employing a carbon layer between the solvent soluble layer and the conductive layer

ABSTRACT

An imaging system wherein an imaging member comprising a supporting substrate, a layer of electrically conductive material, a layer comprising carbon, a softenable layer comprising solvent soluble softenable material contacting said layer comprising carbon, and a layer of particulate material comprising electrically photosensitive material embedded at the surface of said softenable material, is imaged in a migration imaging system wherein said member has an electrical latent image formed thereon and is first developed by contacting said member with a first solvent, and further developed by contacting with a second solvent to form an optically negative or optically positive image comprising carbon on the supporting substrate.

Stes tent [72] Inventors Peter P. Augostini Webster; Mortimer Levy, Rochester, both 01 NY.

[21] Appl. No. 694,906

[22] Filed Jan. 2, 1968 [45] Patented Oct. 26, 1971 [73] Assignee Xerox Corporation Rochester, NY.

[54] MIGRATION IMAGING SYSTEM EMPLOYING A CARBON LAYER BETWEEN THE SOLVENT SOLUBLE LAYER AND THE CONDUCTIVE LAYER 48 Claims, 6 Drawing Figs.

[52] IJ.S.CI 96/15,

[51] Jim. C1. ..G03g 13/22,

603g 5/06 [50] Field of Search 96/1, 1.5, 1.8; 117/37, 17.5, 1,218

[56] References Cited UNITED STATES PATENTS 3,446,616 5/1969 Clark 96/1.5

Primary Examiner-George F. Lesrnes Assistant Examiner-John C. Cooper, 111

Attorneys-James J. Ralabate, David C. Petre and Roger W.

Parkhurst ABSTRACT: An imaging system wherein an imaging member comprising a supporting substrate, a layer of electrically conductive material, a layer comprising carbon, at softenable layer comprising solvent soluble softenable material contacting said layer comprising carbon, and a layer of particulate material comprising electrically photosensitive material embedded at the surface of said softenable material, is imaged in a migration imaging system wherein said member has an electrical latent image formed thereon and is first developed by contacting said member with a first solvent, and further developed by contacting with a second solvent to form an optically negative or optically positive image comprising carbon on the supporting substrate.

PATENTEDnm 26 Ian 3,515,400

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.QQODID... l3 INVENTOR$ 1 PETER RAUGOSTINI MORTIMER LEVY ATTORNEYS MTGRATION IMAGING SYSTEM EMPLOYING A CARBON LAYER BETWEEN THE SOLVENT SOLUBLE LAYER AND 'llllilE CONDUCTIWIE LAYER BACKGROUND OF THE INVENTION This invention relates in general to imaging, and more specifically, to an improved imaging system.

There has recently been developed a migration imaging system capable of producing high-quality images of high density, continuous tone, and high resolution. The system is described and claimed in application Ser. No. 403,002, filed on Oct. 12, 1964 now abandoned. In a typical embodiment of the imaging system, an imaging structure comprising a conducting substrate with a layer of softenable or soluble material, containing photosensitive particles overlying the conducting substrate, is imaged in the following manner: a latent image is formed on the photosensitive surface, e.g., by uniform electrostatic charging, and exposure to a pattern of activating electromagnetic radiation. The softenable layer is then developed by exposing the plate to a solvent which dissolves only the softenable layer. The photosensitive particles which have been exposed to radiation migrate through the softenable layer as it is softened, and dissolved, leaving an image of photosensitive particles on the conducting substrate conforming to a negative of the original. This is known as a positive-to-negative image. Through the use of various techniques, either positive-to-positive or positive-to-negative images may be made depending on the materials used and the charging polarities. Those portions of the photosensitive layer which do not migrate to the conducting substrate may be washed away by the solvent with the softenable layer.

The migration imaging process comprises a combination of process steps which include charging, exposing and developing with a solvent. The characteristics of these images are dependent upon such process steps as charging, exposure and development, as well as the particular combination of the process steps. High density, continuous tone and high resolution are some of the photographic characteristics possible. This image is characterized as a fixed or unfixed photoconductive powder image which can be used in a number of applications, such as microfilm, hard copy, optical masks, and stripout applications using adhesive materials. Alternative embodiments of the concept are further described in the abovecited application.

The instant invention contemplates an improved migration imaging structure and a method which further improves image contrast and density, and affords a simple and efficient method of making either a positive or negative reproduction of an original image.

SUMMARY OF THE INVENTION It is, therefore, an object of this invention to provide an improved imaging system.

It is another object of this invention to provide an improved migration imaging structure.

It is yet another object of this invention to provide an improved migration imaging method capable of producing either positive or negative images.

The foregoing objects and others are accomplished in accordance with this invention by providing a novel migration imaging structure comprising a conductive substrate overcoated with a carbon layer having a softenable or soluble plastic over-coating, containing an overlayer of photosensitive material such as particulate vitreous selenium at its upper exposed surface. This structure is first imaged by the migration imaging techniques described in the above-mentioned application which comprise forming a latent image on the photoconductive surface as by uniform electrostatic charging; followed by exposure to a selective pattern of radiation forming the latent electrostatic image. This image is then developed by immersing in a liquid solvent for the softenable plastic layer resulting in the formation of an image comprising the migrated selenium particles in image configuration overcoating the carbon layer in the areas exposed to light while in the exposed areas, the selenium has been washed away with the remainder of the softenable layer, and only the carbon layer remains. The structure is then subjected to a second developing treatment which comprises immersing it in a second solvent for at least several seconds up to several minutes, and depending upon the concentration of the second solvent, results either in the selenium-carbon portion being washed away or the carbon layer in the unexposed region being washed away, leaving a final image comprising either a dense carbon layer contained on the supporting substrate, or a combination of the selenium-carbon layer contained on the substrate. The final image, whether it be carbon in the form of a positive image or a composite of carbon-selenium in the form of a negative image, has exceptionally high density superior to that presently obtained using conventional photosensitive materials alone, such as for example, selenium.

BRIEF DESCRIPTION OF Til-IE DRAWINGS The advantages of this improved structure and method will become apparent upon consideration of the following disclosure, especially when taken in conjunction with the accompanying drawings wherein:

FIG. l is a schematic illustration of one embodiment of a typical structure contemplated by this invention.

FIG. 2 illustrates charging the structure of FIG. ll.

FIG. 3 illustrates exposing the charged structure to a pattern of activating radiation.

FIG. 4 illustrates developing the structure of FIG. 3.

FIG. 5 illustrates a second development step.

FIG. 6 illustrates another embodiment of the second development step.

Referring to FIG. 1, there is shown one embodiment of an imaging structure contemplated by this invention, comprising an imaging plate or film 10. The substrate of the structure may comprise any suitable electrical conductor. Typical substrates are aluminum, tin oxide, tin, and indium. The substrate may be in any form such as a metallic strip, sheet, foil, cylinder, drum or the like. If desired, the conductive substrate l2,may be coated in a thin film on an insulator llll such as paper, glass or a plastic which are insoluble to the solvents used in development. One example of this type of substrate comprises NESA glass, which is a partially transparent tin-oxide-coated glass available from Pittsburgh Plate Glass Co. Another typical substrate comprises aluminized Mylar, which is made up of a Mylar polyester film from E. I. duPont de Nemours Co., Inc., having a thin semitransparent aluminum coating.

Layer 13 comprises a carbon or a carbonacious layer made up essentially of particulate carbon in a thickness from about 0.1 to 3 microns. The carbon may be used in any suitable form. Typical forms include graphite, charcoal, coke, carbon black, lamp black, and activated carbon. The size of the carbon particles may range in size up to about 1 micron but preferably are in a size ranging from about 0.01 to 0.5 microns. This particle size is critical inasmuch as particles in this size range exhibit excellent adhesion to the substrate, and allow for careful control in thickness of the carbon layer. A particularly preferred source of carbon consists of a water base colloidal suspension of carbon (22 percent colloidal graphite) in water available under the tradename Aquadag from Acheson Colloids Corp., Port Huron, Mich. The carbon layer is formed by uniformly coating the dag over the supporting substrate in a suitable thickness, and allowing the coating to dry either in air or by slightly heating. Other means of forming the carbon layer also may be employed. For example, the layer may be formed by simply dusting or cascading elemental carbon particles over the supporting substrate.

The softenable plastic layer 14 may be of any suitable material which is soluble in any suitable solvent, and in addition, is substantially electrically insulating during the imaging and developing cycle. Classes of materials falling within this definition include polystyrenes, alkyd substituted polystyrenes, polyolefins, styrene-acrylate copolymers, styrene-olefin copolymers, silicone resins, phenolic resins, and organic amorphous glasses. Typical materials are Staybelite Ester 10, a partially hydrogenated rosin ester, Foral Ester, a hydrogenated rosin triester, and Neolyne 23, an alkyd resin, all from Hercules Powder Co., SR 82, SR 84, silicone resins, both obtained from General Electric Corporation; Sucrose Benzoate, Eastman Chemical; Velsicol X-37, a polystyreneolefin copolymer from Velsicol Chemical Corp.; Hydrogenated Piccopale 100, a highly branched polyolefin, Piccotex 100, a copolymer of methyl styrene and vinyl toluene, Piccolastic A-75, 100 and 125, all polystyrenes, Piccodiene 2215, a polystyrene-olefin copolymer, all from Pennsylvania Industrial Chemical Co., Araldite 6060 and 6071, epoxy resins of Ciba; Amoco 18, a polyalpha' rnethylstyrene from Amoco Chem. Corp.; ET-693, and Amberol ST, phenol-formaldehyde resins, ethyl cellulose, and Dow C4, a methylphenylsilicone, all from Dow Chemical; M-l40, a custom synthesized styrene-co-n-butylmethacrylate, R5061A, a phenylmethyl silicone resin, from Dow Corning; Epon 1001, a bisphenol A-epichlohydrin epoxy resin, from Shell Chemical Corp., and PS-2, PS-3, both polystyrenes, and ET-693, a phenol-formaldehyde resin, from Dow Chemical; and a custom synthesized 80/20 mole percent copolymer of styrene and hexylmethacrylate having an intrinsic viscosity of 0.179 dl./gm.

In general, the softenable or soluble layer should be from about 1% to 16 microns in thickness, and may be prepared by any suitable technique. Typical methods of preparation include dip coating, roll coating, draw coating, or pour coating, with better control and more uniform results being obtained with dip and roll coating techniques. Thicknesses below 1% micron do not allow a sufficient depth for particle migration imaging. Thicker layers generally requiring a greater potential for charging, and in general, a thickness from about 1 to microns has been found to yield particularly good results.

The above group of materials is not intended to be limiting, but merely illustrative of materials suitable for the softenable plastic layer.

The material comprising layer may consist of any suitable inorganic or organic photosensitive material. Typical inorganic materials are vitreous selenium, vitreous selenium a1- loyed witharsenic, tellurium, antimony or bismuth, etc., cadmium sulfide, zinc oxide, cadmium sulfoselenide, and many others. U.S. Pat. No. 3,121,006 to Middleton et al. sets forth a whole host of typical inorganic pigments. Typical organic materials are: Watchung Red B, a barium salt of l-(4-methyl- 5'-chloro-azo-benzene-2'-sulfonic acid)-2-hydrohydroxy-3- napthoic acid, C. I. No. 15865, available from duPont; Indofast double scarlet toner, a Pyranthrone-type pigment available from Harmon Colors; quindo magenta RV-6803, a quinacridone-type pigment available from Harmon Colors; quinacridones, such as Monastral Red B (E. I. duPont), Cyan Blue, GTNF the beta form of copper phthalocyanine, C. I. No. 74160, available from Collway Colors; Monolite Fast Blue GS, the alpha form of metal-free phthalocyanine, C. I. No. 74100, available from Arnold Hoffman Co.; Diane Blue, 3,3-methoxy-4,4'-diphenyl-bis 1" ale-2" hydroxy-S' -naphthanilide), C. I. No. 21180, available from Harmon Colors; and Algol G. C., polyvinyl carbazole, 1,2,5,6-di (D,D'-diphenyl)-thiazoleanthraquinone, C. I. No. 67300, available from General Dyestuffs. The above list of organic and inorganic photosensitive materials is illustrative of some of the typical materials, and should not be taken as a complete listing.

The photosensitive particles of layer 15 may be formed by any suitable method. Typical methods include vacuum evaporation; cascading the material while being carried on glass beads or other suitable carrier over the soluble layer 14 which has been softened by a solvent vapor and/or heat; liquid development techniques; powder cloud development techniques; by slurry coating techniques; or by simply dusting the particles of photosensitive material over the slightly softened soluble material.

In addition to the configuration shown in FIG. 1 additional modifications in the layered structure are also included within the scope of this invention. One such modification includes an overcoated layered structure in which a layer of photosensitive particles is sandwiched between two or more layers of the softenable material which overlie the conductive substrate.

The thickness of the particulate layer and size of the photoconductive particles is usually less than about 1 micron, with the particle size ranging from about 0.01 to 2.0 microns. Particles larger than about 2.0 microns do not yield optimum resolution and also show a reduction in image density compared to images having particles less than about 2.0 microns.

The structure or plate 10 of FIG. 1 may be imaged by uniformly electrostatically charging the surface with a corona charging unit 16 such as illustrated in FIG. 2. The applied field for the structures of this invention ranges from a few volts to several hundred volts per micron of softenable plastic layer 14. It should be understood that other charging techniques well-known in the art may also be used in carrying out the instant invention. Typical methods include corona charging through a mask or stencil, or forming a latent image directly through the use of a shaped electrode or pin matrix. The charged plate, where substantially uniformly charged as illustrated in FIG. 2, is then exposed to a pattern of activating radiation 17 such as light, as shown in FIG. 3. The plate is then developed in a liquid solvent 18, which first softens and dissolves away soluble layer 14 resulting in the formation of an image composed of the light-struck photosensitive particles 15 contained in image configuration on the carbon layer 13 as illustrated in FIG. 4. Solvent 18 may comprise any suitable solvent for softenable plastic layer 14 in which the remaining materials of the imaging structure (substrate, conductive film, carbon layer, and photosensitive layer) are substantially insolvent. Typical solvents are listed in application Ser. No. 403,002, now abandoned, and include without limitation; cyclohexane, trichloroethylene, xylene, toluene, pentane, 1,1,l-trichloroethylene, methyl ethyl ketone, ethylene dichloride, methylene chloride, carbon tetrachloride, and triophene.

The structure of FIG. 4 is then further treated by exposure to a dilute solvent 19 as illustrated in FIG. 5. The treatment is carried out for at least several seconds up to several minutes, which results in the washing away of the composite photosensitive carbon image, and leaves an image comprising the carbon layer only in the form ofa positive image shown as in FIG. 5. When a concentrated solvent 20 is used, the single carbon layer is removed and a combination of photosensitive particles over the carbon layer in the form of a negative image remains as illustrated in FIG. 6.

It can be seen that the second development or solvent treatment illustrated in FIGS. 5 and 6 results in the thin conductive coating 12 being completely dissolved or washed away no matter what the concentration of the solvent. It is believed that the removal of the conductive film is essential in forming the images of the instant invention, and therefore the solvent used in the second development treatment should be capable of dissolving the conductive film 12. The table below lists various typical combinations of conductive films and developing solvents, which are suitable for image formation such as that illustrated in FIGS. 5 and 6. Typical solvents include acids and strong bases. Dilute solvents result in the formation of a positive image comprising carbon as illustrated in FIG. 5, while concentrated solvents result in the formation of a negative image comprising a composite of photosensitive particles over a carbon layer as shown in FIG. 6.

TABLE Aluminum Tin Oxide Alkaline solutions such as sodium sulfuric. hydrochloric Potassium Cyanide Hydrochloric acid.

potassium Iodide. Sulfuric Acid. and Liquid ammonia Cuprous Sulfide Cupric Iodide A particularly preferred developing solvent 19 or 20 for the second solvent treatment comprise any suitable alkaline solution. Typical solutions include sodium hydroxide, potassium hydroxide, sodium sulfide, and calcium hydroxide. Relatively dilute solutions, such as 1 normal, 3 normal, 6 normal, result in the formation of the negative image, while solutions having a greater concentration, such as about 50 percent, result in the formation of the negative image. In general, any alkaline solution of proper concentration to remove either the exposed or unexposed portions of the solvent developed area illustrated in FIG. 4 may be used in the second or final development step illustrated in FIGS. 5 and 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples specifically define the present invention with respect to a method of making and imaging a migration imaging structure. The parts and percentages in the disclosure, examples, and claims are by weight unless otherwise indicated. Examples are intended to illustrate the various preferred embodiments of making and imaging a migration imaging structure.

Example I An imaging film or plate about 1X3 inches in size, such as that illustrated in FIG. ii, is made by coating ml. of a water base colloidal suspension of 22 percent carbon, available from Acheson Colloids Corp. under the trade name Aquadag, (the dag is further diluted in 100 ml. of water) with a 950 gravure roller onto a 3-mil aluminized Mylar substrate. Rotoproofer Analox Rollers by Pamarco, Inc. Roselle, NJ. are designated sizes 55Q to 2000. The coating process is carried out to form a 2-micron coating of carbon when dried for 2 hours in hot air at about 100 C. The carbon layer is then overcoated with a softenable plastic layer by making a solution of percent by weight of Staybelite Ester 10 (a 50 percent hydrogenated glycerol rosin ester of the I-Iercules Powder Co.), dissolved in toluene. Using a gravure roller, the mixture is then roll coated over the carbon layer. The coating is applied so that when airdried for about 2 hours at 50 C. to allow for evaporation of the toluene, an imaging plate comprising a 2-micron layer of Staybelite Ester is formed on the carbon layer. A thin layer of particulate vitreous selenium approximately 0.5 microns in thickness is then deposited onto the Stabelite surface by inert gas deposition utilizing the process set forth in patent application Ser. No. 423,167, filed on Jan. 4, 1965, now abandoned.

Example II Three additional plates or films were made by the method of Example I. These plates were made using gravure rollers for forming the carbon layer having sizes of 720, 1200, and 2000, respectively, and this resulted in a carbon layer thickness ranging from about 3 microns for the 72Q roller, down to about A; microns for the 200Q roller.

Example III All four films prepared by Examples I and II are imaged by uniformly charging to a positive potential of about 60 or 70 volts with a corona-charging device, such as that described by Carlson in US. Pat. 2,588,699. The films are then exposed to a pattern of light with the energy in the illuminated areas being about 5 foot-candle-seconds by means of a tungsten lamp. The films are then developed by immersing them in a bath of liquid cyclohexane for about 2 seconds. Each film exhibits an excellent reproduction of the original pattern of light in the form of selenium particles deposited over the carbon layer in the areas struck by light, while in the areas not exposed to light. a carbon layer remains over the Mylar substrate. This configuration is illustrated by FIG. 4 of the drawings.

Example IV Each of the four films of Example III are cut into two equal portions about 1 inch X 11% inches with each portion having part of a developed image, such as illustrated by FIG. 4. One portion of each of the films is then developed by immersing it for about 5 seconds in a 1 normal alkaline bath of sodium hydroxide. Each of the 4 portions exhibits a carbon image, representing a positive image of an original, in which only a carbon image remains on the Mylar substrate in the areas which were unexposed to light. This configuration is illustrated by FIG. 5.

The second portion of each of the f our films is immersed in a 50 percent sodium hydroxide solution for about 5 seconds. This development results in the formation of a negative image on each of the four samples comprising a combination of selenium particles overlying a carbon layer in the areas which had previously been exposed to light. This configuration is illustrated in FIG. 6 of the drawings.

It can be seen from the above examples that the second solvent treatment results in the selective formation of either a high-density positive or negative image, with relatively weak or dilute solutions resulting in the formation of a positive image and more concentrated solutions forming a negative image. The other solvents defined in the table can be used in a manner similar to the alkaline solutions used in the examples.

Although specific components and proportions have been stated in the above description of the preferred embodiment of this invention, other suitable materials and procedures such as those listed above may be used with similar results. In addition, other materials and changes may be utilized which synergize, enhance, or otherwise modify applicants novel layered structure.

Other modifications and ramifications of the present invention would appear to those skilled in the art upon reading this disclosure. These are intended to be within the scope of this invention.

What is claimed is:

I. An imaging member comprising:

an electrically conductive supporting substrate;

a layer consisting essentially of carbon particles overcoating said electrically conductive substrate;

a solvent soluble electrically insulating layer contacting said carbon layer;

and a layer of particulate material. said particulate material comprising electrically photosensitive material, embedded in said soluble layer at the surface of said soluble layer spaced apart from the surface of said soluble layer contacting the carbon layer and said soluble layer is soluble in a solvent wherein said substrate, carbon particles and particulate material comprising photosensitive material are substantially insoluble.

2. The imaging member of claim 1 wherein the carbon layer is of a thickness in the range between about 0.1 and about 3 microns.

3. The imaging member of claim 1 wherein said particles comprising carbon are of a size not greater than about 1 micron.

4. The imaging member of claim I wherein said particles comprising carbon are of a size in the range between about 0.01 and about 0.5 microns.

5. The imaging member of claim 1 wherein said soluble layer is of a thickness in the range between about one-half and about 16 microns.

6. The imaging member of claim 5 wherein said soluble layer is of a thickness in the range between about 1 and about 5 microns.

7. The imaging member of claim 1 wherein said photosensitive particulate material comprises particles of size in the range between about 0.01 and about 2 microns.

8. The imaging member of claim 7 wherein said particulate material is of a size not greater than about 1 micron.

9. The imaging member of claim 8 wherein the layer of particulate material is of a thickness not greater than about 1 micron.

10. The imaging member of claim 1 wherein said photosensitive material comprises photoconductive material.

'1 1. The imaging member of claim 1 wherein said electrically photosensitive material comprises selenium.

12. The imaging member of claim 1 wherein said member additionally comprises a second solvent soluble electrically insulating layer overcoating the first soluble layer and the layer of particulate material.

13. An imaged member comprising a substrate and areas in imagewise configuration on said substrate, said areas in imagewise configuration comprising: a layer in imagewise configuration overcoating said substrate and consisting essentially of carbon particles and a layer of particulate material in said imagewise configuration, said particulate material comprising electrically photosensitive material overcoating said carbon layer.

14. The imaged member of claim 13 wherein the carbon layer is of a thickness in the range between about 0.1 and about 3 microns.

15. The imaged member of claim 13 wherein said carbon particles are of a size not greater than about 1 micron.

16. The imaged member of claim 15 wherein said carbon particles are of a size in the range between about 0.01 and about 0.5 microns.

17. The imaged member of claim 13 wherein said particulate material comprising photosensitive material comprises particles of a size in the range between about 0.01 and about 2 microns.

18. The imaged member of claim 17 wherein said particulate material comprising photosensitive material is of a size not greater than about 1 micron.

19. The imaged member of claim 13 wherein said electrically photosensitive material comprises photoconductive material.

20. The imaged member of claim 13 wherein said electrically photosensitive material comprises selenium.

21. An imaging method comprising:

providing a member comprising a supporting substrate, a

layer of electrically conductive material overcoating said supporting substrate, a layer consisting essentially of carbon particles overcoating said electrically conductive layer, and particulate material in imagewise configuration on said carbon layer; and

contacting said member with a solvent capable of dissolving said conductive layer; said supporting substrate, carbon layer, and particulate material being substantially insoluble in said solvent; whereby portions of the conductive layer are dissolved and portions of the carbon layer are washed away leaving a visible image on the supporting substrate.

22. The method of claim 21 wherein said member is provided by steps comprising:

providing an imaging member comprising an electrically conductive supporting substrate, a layer consisting essentially of carbon particles overcoating said electrically conductive substrate, a solvent soluble electrically insulating layer contacting said carbon layer, and a layer of particulate material, said particulate material comprising electrically photosensitive material, embedded in said soluble layer at the surface of said soluble layer spaced apart from the surface of said soluble layer contacting the carbon layer;

forming an electrical latent image on said imaging member;

and

contacting said member with a liquid solvent capable of substantially dissolving said solvent soluble layer, the

other elements of said imaging member being substantially insoluble in said solvent, whereby particulate material migrates in imagewise configuration to the carbon layer which remains substantially intact over the supporting substrate.

23. The method of claim 22 wherein said electrically conductive supporting substrate comprises a supporting substrate and a layer of electrically conductive material overcoating the supporting substrate between said substrate and the carbon layer.

24. The method of claim 21 wherein the carbon layer is of a thickness in the range between about 0.1 and about 3 microns.

25. The method of claim 21 wherein said particulate material comprises particles of size in the range between about 0.01 and about 2 microns.

26. The method of claim 25 wherein said particulate material is of a size not greater than about 1 micron.

27. The method of claim 26 wherein the layer of particulate material is of a thickness not greater than about 1 micron.

28. The method of claim 21 wherein the solvent comprises a chemically basic solution having pH greater than 7.

29. The method of claim 28 wherein said solvent comprises a solution of sodium hydroxide.

30. The method of claim 28 wherein said solvent comprises a chemically basic solution of concentration not greater than about 6 N, whereby an optically positive image comprising carbon is formed on the supporting substrate.

31. The method of claim 30 wherein said solution has a concentration not greater than about 1 N.

32. The method of claim 30 wherein said solvent comprises a solution of sodium hydroxide.

33. The method of claim 28 wherein said solvent comprises a chemically basic solution having a concentration greater than about 6 N, whereby an optically negative image comprising carbon is formed on the supporting substrate.

34. The method of claim 33 wherein said image additionally comprises photosensitive particles overlying the image comprising carbon.

35. The method of claim 33 wherein said second solvent comprises a solution of sodium hydroxide.

36. The method of claim 33 wherein said image additionally comprises particulate material overlying the image comprising carbon.

37. The method of claim 22 wherein the carbon layer is of a thickness in the range between about 0.1 and about 3 microns.

38. The method of claim 22 wherein said carbon particles are of a size not greater than about 1 micron.

39. The method of claim 22 wherein said carbon particles are of a size in the range between about 0.01 and about 0.5 microns.

40. The method of claim 22 wherein said electrical latent image is formed by steps comprising uniformly electrically charging the imaging member, and

exposing said member to an imagewise pattern of activating electromagnetic radiation.

41. The method of claim 22 wherein said electrical latent image comprises an electrostatic latent image.

42. The method of claim 21 wherein said carbon particles are of a size not greater than about 1 micron.

43. The method of claim 21 wherein said carbon particles are of a size in the range between about 0.01 and about 0.5 microns.

44. The method of claim 22 wherein said soluble layer is of a thickness in the range between about one-half and about 16 microns.

45. The method of claim 22 wherein said soluble layer is of a thickness in the range between about 1 and about 5 microns.

46. The method of claim 22 wherein said photosensitive material comprises photoconductive material.

'47. The method of claim 22 wherein said electrically photosensitive material comprises selenium.

48. The method of claim 22 wherein said member additionally comprises a second soluble layer overcoating the first soluble layer and the layer of particulate material.

PO-IOEO (5/68) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 615,400 Dated October 26, 1971 Inventor(s) Peter P. Augostini and Mortimer Levy It is certified that error a ppears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 2, delete "exposed" and insert -unexposed.

Signed and sealed this 2nd day of May 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Com issioner of Patents 

2. The imaging member of claim 1 wherein the carbon layer is of a thickness in the range between about 0.1 and about 3 microns.
 3. The imaging member of claim 1 wherein said particles comprising carbon are of a size not greater than about 1 micron.
 4. The imaging member of claim 1 wherein said particles comprising carbon are of a size in the range between about 0.01 and about 0.5 microns.
 5. The imaging member of claim 1 wherein said soluble layer is of a thickness in the range between about one-half and about 16 microns.
 6. The imaging member of claim 5 wherein said soluble layer is of a thickness in the range between about 1 and about 5 microns.
 7. The imaging member of claim 1 wherein said photosensitive particulate material comprises particles of size in the range between about 0.01 and about 2 microns.
 8. The imaging member of claim 7 wherein said particulate material is of a size not greater than about 1 micron.
 9. The imaging member of claim 8 wherein the layer of particulate material is of a thickness not greater than about 1 micron.
 10. The imaging member of claim 1 wherein said photosensitive material comprises photoconductive material.
 11. The imaging member of claim 1 wherein said electrically photosensitive material comprises selenium.
 12. The imaging member of claim 1 wherein said member additionally comprises a second solvent soluble electrically insulating layer overcoating the first soluble layer and the layer of particulate material.
 13. An imaged member comprising a substrate and areas in imagewise configuration on said substrate, said areas in imagewise configuration comprising: a layer in imagewise configuration overcoating said substrate and consisting essentially of carbon particles and a layer of particulate material in said imagewise configuration, said particulate material comprising electrically photosensitive material overcoating said carbon layer.
 14. The imaged member of claim 13 wherein the carbon layer is of a thickness in the range between about 0.1 and about 3 microns.
 15. The imaged member of claim 13 wherein said carbon particles are of a size not greater than about 1 micron.
 16. The imaged member of claim 15 wherein said carbon particles are of a size in the range between about 0.01 and about 0.5 microns.
 17. The imaged member of claim 13 wherein said particulate material comprising photosensitive material comprises particles of a size in the range between about 0.01 and about 2 microns.
 18. The imaged member of claim 17 wherein said Particulate material comprising photosensitive material is of a size not greater than about 1 micron.
 19. The imaged member of claim 13 wherein said electrically photosensitive material comprises photoconductive material.
 20. The imaged member of claim 13 wherein said electrically photosensitive material comprises selenium.
 21. An imaging method comprising: providing a member comprising a supporting substrate, a layer of electrically conductive material overcoating said supporting substrate, a layer consisting essentially of carbon particles overcoating said electrically conductive layer, and particulate material in imagewise configuration on said carbon layer; and contacting said member with a solvent capable of dissolving said conductive layer; said supporting substrate, carbon layer, and particulate material being substantially insoluble in said solvent; whereby portions of the conductive layer are dissolved and portions of the carbon layer are washed away leaving a visible image on the supporting substrate.
 22. The method of claim 21 wherein said member is provided by steps comprising: providing an imaging member comprising an electrically conductive supporting substrate, a layer consisting essentially of carbon particles overcoating said electrically conductive substrate, a solvent soluble electrically insulating layer contacting said carbon layer, and a layer of particulate material, said particulate material comprising electrically photosensitive material, embedded in said soluble layer at the surface of said soluble layer spaced apart from the surface of said soluble layer contacting the carbon layer; forming an electrical latent image on said imaging member; and contacting said member with a liquid solvent capable of substantially dissolving said solvent soluble layer, the other elements of said imaging member being substantially insoluble in said solvent, whereby particulate material migrates in imagewise configuration to the carbon layer which remains substantially intact over the supporting substrate.
 23. The method of claim 22 wherein said electrically conductive supporting substrate comprises a supporting substrate and a layer of electrically conductive material overcoating the supporting substrate between said substrate and the carbon layer.
 24. The method of claim 21 wherein the carbon layer is of a thickness in the range between about 0.1 and about 3 microns.
 25. The method of claim 21 wherein said particulate material comprises particles of size in the range between about 0.01 and about 2 microns.
 26. The method of claim 25 wherein said particulate material is of a size not greater than about 1 micron.
 27. The method of claim 26 wherein the layer of particulate material is of a thickness not greater than about 1 micron.
 28. The method of claim 21 wherein the solvent comprises a chemically basic solution having pH greater than
 7. 29. The method of claim 28 wherein said solvent comprises a solution of sodium hydroxide.
 30. The method of claim 28 wherein said solvent comprises a chemically basic solution of concentration not greater than about 6 N, whereby an optically positive image comprising carbon is formed on the supporting substrate.
 31. The method of claim 30 wherein said solution has a concentration not greater than about 1 N.
 32. The method of claim 30 wherein said solvent comprises a solution of sodium hydroxide.
 33. The method of claim 28 wherein said solvent comprises a chemically basic solution having a concentration greater than about 6 N, whereby an optically negative image comprising carbon is formed on the supporting substrate.
 34. The method of claim 33 wherein said image additionally comprises photosensitive particles overlying the image comprising carbon.
 35. The method of claim 33 wherein said second solvent comprises a solution of sodium hydroxide.
 36. The method of claim 33 wherein said imAge additionally comprises particulate material overlying the image comprising carbon.
 37. The method of claim 22 wherein the carbon layer is of a thickness in the range between about 0.1 and about 3 microns.
 38. The method of claim 22 wherein said carbon particles are of a size not greater than about 1 micron.
 39. The method of claim 22 wherein said carbon particles are of a size in the range between about 0.01 and about 0.5 microns.
 40. The method of claim 22 wherein said electrical latent image is formed by steps comprising uniformly electrically charging the imaging member, and exposing said member to an imagewise pattern of activating electromagnetic radiation.
 41. The method of claim 22 wherein said electrical latent image comprises an electrostatic latent image.
 42. The method of claim 21 wherein said carbon particles are of a size not greater than about 1 micron.
 43. The method of claim 21 wherein said carbon particles are of a size in the range between about 0.01 and about 0.5 microns.
 44. The method of claim 22 wherein said soluble layer is of a thickness in the range between about one-half and about 16 microns.
 45. The method of claim 22 wherein said soluble layer is of a thickness in the range between about 1 and about 5 microns.
 46. The method of claim 22 wherein said photosensitive material comprises photoconductive material.
 47. The method of claim 22 wherein said electrically photosensitive material comprises selenium.
 48. The method of claim 22 wherein said member additionally comprises a second soluble layer overcoating the first soluble layer and the layer of particulate material. 